Construction

Synthetic fibers in use for rope-making include polypropylene, nylon, polyesters (e.g. PET, LCP, HPE, Vectran), polyethylene (e.g. Spectra), Aramids (e.g. Twaron, Technora and Kevlar) and polyaramids (e.g. Dralon, Tiptolon). Some ropes are constructed of mixtures of several fibres or use co-polymer fibres. Rope can also be made out of metal. Ropes have been constructed of other fibrous materials such as silk, wool, and hair, but such ropes are not generally available. Rayon is a regenerated fiber used to make decorative rope.

Usage

Rope is of paramount importance in fields as diverse as construction, seafaring, exploration, sports and communications and has been since prehistoric times. In order to fasten rope, a large number of knots have been invented for various uses. Pulleys are used to redirect the pulling force to another direction, and may be used to create mechanical advantage, allowing multiple strands of rope to share a load and multiply the force applied to the end. Winches and capstans are machines designed to pull ropes.

Climbing Ropes: Climbing ropes have a "kernmantle" construction consisting of a braided core, which supplies most of the rope's strength. The core is covered by a woven sheath. Kernmantle ropes are durable and easy to knot. More importantly, they are dynamic. They stretch. When falling, say 50 feet, the rope will stretch five to seven feet (average) to gradually absorb the impact. By applying the brakes this way, a climbing rope catches the climber gently, lessening the force on the climber as well as his/her gear. "Static" ropes used in caving and sport rappelling hardly stretch at fall. Fall on one of these and the jolt it delivers could break the climber's gears or even the climber him/herself. The UIAA (Union Internationale des Association d'Alpinisme) in concert with the CE sets climbing-rope standards and oversees testing. Any rope bearing a UIAA or CE certification tag is fine for climbing. Despite the hundreds of thousands of falls climbers suffer every year, there is not a single recorded instance of a climbing rope breaking in a fall. Climbing ropes, however, do cut easily when they are weighted. Keeping them away from sharp rock edges and old worn carabiners is imperative. Ropes come with either a designation for Single, or Double(Twin) use. A single rope is the most common and it is intended to be used by itself, as a single strand. Single rope range in thickness from roughly 9mm to 11mm. Smaller ropes are lighter, but wear out faster. Double ropes are thinner ropes, usually 9mm and under, and are intended to be used as a pair. These ropes offer a greater margin or security against cutting, since it is unlikely that both ropes will be cut, but complicate belaying and leading. Double ropes are usually reserved for ice and mixed climbing, where there is need for two ropes to rappel.